1. Field of the Invention
This invention relates to a process for treating plant materials to remove color and flavor for providing a lighter colored, blander tasting flour; and in particular to providing a flour of sufficient whiteness for use in food products. By treating fibrous material, a flour with a relatively high dietary and low crude fiber content is formed.
2. Description of the Prior Art
A primary source of lightly colored fiber presently used in fiber flours for bakery goods is obtained by processing bark and other by-products of trees, the fiber thus obtained being mostly crude fiber. The fiber flour is produced from an acceptable "food source", however, there is growing concern about eating what is referred to as a "furniture fiber". Also, fiber from cottonseeds is being produced and marketed, however, the fiber obtained is mostly crude fiber and again there is concern about eating what is referred to as "clothes fiber".
For over a half century, technology for bleaching bread flours has been well researched and defined by the baking industry. "Bleaching as it relates to edible flour is defined as the removal of color by oxidation of the yellow flour pigment"; "coloring matter of bran is not effected by bleaching agents", (Pyler, Baking Science and Technology, Siebel Publishing Company, second printing 1979). A review of the prior art shows scientists exposing cereal grain flour to, for example, nitrogen peroxide, chlorine, nitrogen trichloride, benzoyl peroxide and enzyme active legume flours for the improvement of color (whitening the yellow pigment) and maturing and improving wheat flour. Through the years the industry has, for the most part, settled on the use of enzyme active legume flours (lipoxidase found in pea and soy flours) and benzoyl peroxide (such as "LA Novadelox"), for removing color from cereal grain flour used in making bread. Other methods have fallen by the wayside. Techniques applicable for the removal of yellow color (carotinoids) do not work for the removal of green color (chlorophyll) or darker brown colors.
Many techniques have been developed for bleaching a yellow fiber, a more neutral color than green or brown, however, green or brown are colors that are much more difficult to bleach in order to obtain a desirable light colored, and especially to near white or white, bran material. In developing a desire bleaching process one would have to consider the number of bleaching agents available such as nitrogen peroxide, hydrogen peroxide, organic peroxides, chlorine, chlorine dioxide, hypochlorites, nitrogen trichloride, sulfites, bisulfites, meta-bisulfites, lipoxidases, alcohol, etc. Further, there is the aspect of having to consider the possible number of combinations of such bleaching agents and process parameters, including acidity, alkalinity, temperature, dilutions, processing times, states of matter (solid, liquid and gas), additives, delivery systems, general procedures, etc.
One of the earliest patents that I am aware of relative to bleaching cereal grains is Cooper and Westgate (U.K. patent no. 8091, dated October 1903) which discloses conditioning or improving the quality and color of bran or fibrous tissue of wheat or other cereals by exposing them to chemical sulphur or chlorine in a gaseous form. Tests that I have made show that the application of chlorine gas does not satisfactorily whiten brown (yellow pea hull) or green (green pea hull) material for use in food products.
Australian patent 8,292 (1927) to Buhler, Canadian patent 502,162 to Houtgraaf and U.S. Pat. No. 2,478,043 to Evans teach the application of chlorine in the form of chlorine dioxide to bleach or mature cereal grain flours or bran. Buhler discloses chlorine in an acid form is undesirable for shortening the maturing or bleaching of wheat flour because of the increase in the acid content of the flour itself; and that chlorine dioxide, a more alkaline compound, is more desirable. Buhler applied chlorine in a gaseous or liquid state dissolved in an organic or an inorganic solvent, not in an aqueous dispersion such as in the present invention.
Houtgraaf acknowledges that chlorine dioxide has a favorable influence on bakery flour but was used to a small extent because of the difficulty in preparation and measuring correct quantities of chlorine dioxide. The Houtraaf invention is directed to a method for accurately metering gas to be applied in a dry system wherein an aqueous solution containing the chlorine dioxide is supplied in degassing apparatus and then the product to be treated is subjected to chlorine in a gas stream. Houtgraaf discloses using 5-15 grams of chlorine dioxide per liter.
Evans, U.S. Pat. No. 2,478,043, discloses that the amount of an agent such as chlorine, hydrogen peroxide and nitrogen trichloride for bleaching carotene and related bran pigments is so much greater than that required to bleach bread flour that the treatment deleteriously effects the flour. This patent suggest treating the whole wheat kernel topically with the oxidizing agent at 2 to 8 ozs. per 280 lbs. of wheat in the presence of water. The results of tests conducted under my direction of applying chlorine dioxide in the ranges recommended by Evans and Houtgraaf to yellow and green pea hulls and as outlined by Buhler, Houtgraaf and Evans showed that the application of chlorine dioxide did not effectively render fibrous materials white, or off-white or reduce flavor levels. In fact, during treatment with chlorine dioxide, fibrous material developed a deeper brown color and less desirable off taste.
Baker, U.S. Pat. No. 2,379,335, added chlorine dioxide to water used to temper cereal grain to prevent bacterial and mold growth as well as bleaching the exterior portions of wheat and water extractable materials. The method disclosed for bleaching water extractable coloring matter from cereal grains is by treating grain with either (1) a dilute mixture of chlorine dioxide and chloride in air in an aqueous solution with an added non-volatile inorganic water soluble alkaline substance or (2) a dilute mixture of chlorine dioxide, a peroxide and a water soluble alkali substance. Baker discloses using 30-500 ppm each of chlorine dioxide and chlorine for 1-5 minutes.
Thompson, patent U.S. Pat. No. 4,307,121, discloses a method for isolating cellulose by solubilizing and removing non-cellulosic components from such yellow pigmented fibers as yellow soybean hulls, yellow pea hulls, yellow corn bran, and etc. In particular, the method described is a series of heating, treating (3 separate applications of chlorine and one application of caustic) and extraction steps. The first treatment is in a saturated chlorine solution for a period of six to eighteen hours. A white powder to be added to bread formulations is the end results. However the process disclosed in this patent results in the loss of all but one of the desirable fiber components (an unbalanced fiber matrix). The results obtained in using the Thompson process, about 50% of the fiber was lost, bread made with cellulose added, as the source of edible fiber, requires the addition of vital wheat gluten and other crutches to obtain a reasonable bread volume.
As to using chlorine as a bleaching agent for flour, one of the early patents that describes a procedure for bleaching flour with chlorine is Hobbs (U.S. Pat. No. 1,131,698) which discloses the addition of one pound of hypochlorite to 2500 pounds of wheat flour (a dry blend) for 24 hours as being effective. This amounts to 4,000 ppm. Hobb's recommends the addition of an acid to neutralize the alkalinity to eliminate subsequent delay in the fermentation of bread.
Penn (U.S. Pat. No. 2,087,547) found that a dry free flowing finely powdered chlorine liberating compound, such as calcium hypochlorite, can be reacted with organic peroxides and other peroxidized products to form a gaseous agent to be used to bleach, mature and improve wheat flours and other grain flours, vegetable flour and milling products in general. U.S. Pat. No. 2,192,100 to Penn uses a mixture of an alkaline metal nitrate and active organic peroxide to bleach and mature wheat flour. Benzoyl peroxide used alone in sufficient quantities for complete bleaching of flour reduces volumes of the bakery products obtained and thereby necessitates the addition of the nitrate to overcome the reduction of volumes. Penn--U.S. Pat. No. 2,272,577, discloses that additives such as alkali metal salts can be added to active organic peroxides to prevent flamability of the peroxides.
Both of the Penn patents and Hobbs disclose using dry systems in applying hypochlorite, however, such dry processes do not remove green color from green colored fibers, for example, green pea hulls. U.S. Pat. No. 1,957,333 to Haas and Bohn and U.S. Pat. No. 1,957,335 to Haas disclose enzymatic bleaching or decolorization of carotene from wheat flour, however, on the basis of tests that I have conducted, enzymes such as lipoxidase, do not whiten fibrous materials and the peroxide process of Penn U.S. Pat. No. 2,192,100 does not bleach fibrous materials, for example green pea hulls and parsley.
Farag (U.S. Pat. No. 4,241,093) is directed to obtaining a bland flavored supplement by contacting vegetable or fruit pulp with a number of aqueous bleaching solutions, including sodium hypochlorite, chlorine, chlorine dioxide and hydrogen peroxide and combinations thereof at a 0.5 to 35% range (preferably at the 0.5 to 2% range). Farag, with reference to sugar beet pulp, indicates that his process can be carried out at room temperature but to reduce retention time the process can be carried out at about 60.degree. C. (140.degree. F.) to about 90.degree. C. (194.degree. F.). Farag states that using "temperatures between 60.degree. C. and 80.degree. C. with a bleaching agent concentration of about 1% by weight produces hood results with retention times of from 30 to 60 minutes." However tests that I have conducted and/or under my direction showed that 1% peroxide not effective and at least a 3% peroxide solution is required even when boiling the slurry. While Farag discloses using bleaching solutions at the 35% level, I have found that the addition of chlorine (Cl.sub.2) above about 6.24% starts degradation of the fiber matrix. Additionally my tests indicates the solution overheats and becomes acidic when calcium hypochlorite is added much over the 10% level, having a possible detrimental effect on the product being treated.
Further, my tests confirm the findings in the Beal patent, U.S. Pat. No. 4,451,489, whereby hydrogen peroxide added at the 2% level to sugar beet pulp resulted in an off-flavored and off-colored ingredient contrary to what is disclosed in the Farag patent. Beal relates to the production of a non-caloric sugar beet bulking agent comprised by placing sugar beet pulp material into a stabilizing solution (water soluble bisulfides, sulfities and metabisulfites) to prevent darkening, water washing the product to remove a majority of soluble carbohydrates, contacting the product with an alcoholic solution to remove color and bitter constituents, removing the water and alcohol and milling the product to a flour like consistency. This is in contrast to the present invention wherein chlorine, peroxide or a combination first chlorine and then peroxide is utilized to achieve the desired results.
U.S. Pat. No. 4,649,113 to Gould found that upon adding about a 1% solution of peroxide to non-woody lignocelluloics and adjusting the pH to 11.2 to 11.8, the substrate became partially delignified. That is, Gould is directed to converting plant components to useful carbohydrates for ruminants and microbes which is in contrast to the present invention wherein peroxide is applied in a way not to disturb plant fiber components.
Gould, Penn and Farag do not teach a peroxide treatment at an elevated temperature and a concentration such as discovered by applicant for bleaching a fibrous material to an off-white or white coloration such as set forth hereinafter.
The British patent to Davies, patent no. 688,428, discloses chlorine "bleaching sago flour" (a starch product) while maintaining pH's of either 4-5 or 11-11.5 to prevent a decrease in viscosity during processing. Thereafter hydrogen peroxide is used to remove free chlorine and thence NaOH or HCl is added to the slurry to bring the pH to 6-7 to prevent the otherwise loss of viscosity of the flour. This is in contrast to not having to maintain a pH within a narrow pH range during a bleaching process.
It has been common practice in the food industry to whiten products (such as icings, panned confections, creme fillings, etc., by the addition of titanium dioxide. It has been found that while titanium dioxide can be added to whiten fibrous material, upon processing a product, such as bread, with titanium dioxide added as a whitening agent, an unappealing, unnatural, pastey colored product is the end result.
Patents covering the development of low calorie bakery products include the patents to Glade, Singer, Glickman, Titcomb, and Thompson '018 patents that are referred to below. All of these patents are based on the addition of additives to help carry the fiber.
The Glade U.S. Pat. No. 3,573,061 found that to make an acceptable low calorie bread, the seed coats (the fiber source), the seed coats had to be treated with an acid and an emulsifier selected from the group consisting of egg yolks, lecithin and a combination thereof.
Singer (U.S. Pat. No. 3,574,634) developed a formula whereby the addition of wheat gluten and gum were used to help carry cellulose in bakery, pasta and other foodstuffs to produce food products of lower calorie content. Hydrating the gluten, a protein in wheat, gives the dough rubber-like properties that allows the bread to rise. Without gluten, bread loses the ability to become aerated. Glicksman, U.S. Pat. No. 3,676,150, discovered a way to prepare a low calorie bread product without the addition of wheat gluten. Glicksman's formula requires the addition of cellulose, starch and gums to the product. Glicksman's formula has the advantage over Singer's in that it enables the baker to produce a gluten free bread. Titcomb (U.S. Pat. No. 3,979,523) produced a low calorie white bread eliminating the gum but adding wheat gluten to help carry the inert cellulose. Thompson (U.S. Pat. No. 4,109,018) developed a low calorie bread formulation, calling for the addition of a vital wheat gluten, a second protein source, purified alpha cellulose and a hydrophyllic gum.
U.S. Pat. No. 4,237,170 to Satin and my U.S. Pat. No. 4,711,786, disclose using yellow and green hull fibers for making a bakery product. However, such green or yellow hull fiber flours do not have a color similar to the color of unbleached wheat flour (which has the wheat bran and germ removed), nor a white or off-white color nor a relatively low flavor profile required to formulate a low calorie (1/3 calorie reduction) pleasant tasting white bread or other food product. In the process of '786, triticale was added to mask the undesirable color, odor and flavor.
Soy beans containing about 34% protein, 33% carbohydrate, 18% fat, 10% water and 5% fiber are a good source of protein, fat and fiber. The removal of oil, water and fiber (hulls) commercially results in a dry flour containing about 50% protein. While soy flour is presently being used by the food industry as a protein supplement (bakery items, health drinks, etc.) its usage would be greater if its inherent beany flavor were removed. Researchers have tried for decades to render soy flour bland.
In accordance with tests I have made, peroxide applied to fibrous material as set forth hereinafter remove all types of flavors absorbed and inherent in the product in contrast to adding peroxide to remove free chlorine as set forth in the above Davies patent. Also in accordance with my findings, treating green, yellow and brown fiber with chlorine in a gaseous, dry or liquid form as called for in the Cooper and Westgate, Buhler, Hobbs, Penn, Baker, Evans/Houtgraaf, Farag and Thompson patents does not produce the desired bleaching action such as that obtained by a peroxide application, following the chlorine treatment to produce the action such as set forth hereinafter.
The use of green pea hulls and other green colored vegetable items as a source of fiber that is incorporated as a component of a food product for human consumption, for example, in a bakery product, has been relatively limited due to green coloration and inherent flavors not compatible with consumer tastes, resulting in making the product objectionable to many customers.
In order to obtain a lighter colored (preferably at least off-white, if not white), blander flavor high fiber flour with a better balance of soluble and insoluble fiber from a highly colored fibrous source such as green vegetables and sugar beet pulp and from oat fiber and brown wheat fiber, this invention has been made.